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2nd one has not been unplugged yet. Just found out this morning after reading about it. I could potentially be missing out on more benefits not discovered! Snow is in the way of me doing that haha
2nd one has not been unplugged yet. Just found out this morning after reading about it. I could potentially be missing out on more benefits not discovered! Snow is in the way of me doing that haha
Interesting, hope it all works out and you see further improvements, I don't hear or seen many (or any really) diesel engines doing this mod.
Variable oil pump pressure valve
Variable oil spray nozzle
Variable coolant pump flow
Not sure if im reading this right but it mentions a spray nozzle for the timing chain omitted despite it showing in other charts. Maybe there was two in earlier designs.
Interesting that early OM651s had a 2 channel (oil port) chain tensioner that would constantly fail and wreak havoc with multiple chain failure stories. Later years had a revised tensioner with 4 channel holes and a slightly stiffer spring to provide additional lubrication and better tension. Lost count on the number of revisions. 6 I think?
Decided to go out there and be active with all the snow around.
Looks to be a lot easier to reach solenoid #2 than I thought
#2 pistons squirters control valve unplugged!
Temperature delta is now MUCH closer than before just showing a 20F degree difference between oil temp and coolant (parked but revs held at close to 1,500 rpm)
Normally while driving carefully with it plugged in, I could be hitting 160-170F coolant when oil is just crossing 100-120F. Best of all, NO CEL!
I cant wait to drive this thing!
I am going to search MB EPC to see if I can potentially find a similar screw on piece from a 2008 sprinter, etc. If I can't find anything, I guess I will just have to be creative if a CEL is present
A few hours of research showed this to not be the case as the piston cooling jet valve was included in the initial W204 car. The oil pump solenoid was not fitted until later years along with the block off plug for taxi trims
Decided to go out there and be active with all the snow around.
Looks to be a lot easier to reach than I thought
#2 pistons squirters control valve unplugged!
Temperature delta is now MUCH closer than before just showing a 20F degree difference between oil temp and coolant (parked but revs held at close to 1,500 rpm)
Normally while driving carefully with it plugged in, I could be hitting 160-170F coolant when oil is just crossing 100-120F. Best of all, NO CEL!
I cant wait to drive this thing!
A few hours of research showed this to not be the case as the piston cooling jet valve was included in the initial W204 car. The oil pump solenoid was not fitted until later years along with the block off plug for taxi trims
Very nice : ) I guess that is one advantage of having a four cylinder : )
This interesting video stresses low pump output as the source of modern engine failures.
The pump itself consumes energy to spin... so it got put on diet in the "name of efficiency".
We noted the piston squirters are coined as being the engine largest oil pressure users.
When squirters open up the pump needs to sustain pressure without sudden impact to VVT positioning (MOD-4).
The video sells upgrade with a whole new oil pump. They don't mention anything about "solenoid control" or disabling low pressure mode.
As far as helping the environment you may better than stock by not combusting quarts of engine oil and with stoichiometric mixtures rather than drafty cylinders misfiring lean mixtures.
I didn't pay much attention to the selling point of their upgraded pumps... more along the lines of proof that the design philosophy is flawed, and that any steps that can be taken to reverse this philosophy, say, by unplugging the worthless solenoid that surely has a hand in the causing issues in these engines. Unplug, step up to a better (higher viscosity) engine oil, and let the engine work in a manner that doesn't destroy itself in the process.
I plan on disconnecting it at the cable to see if the oil warms up faster from cold start. Hopefully no CELs and the same piston benefits similar to the gas cars.
Only had the car since August, so my experiencing with storing extreme heat is limited. To answer this question, I have not noticed anything from this.
As far as I know through research, the OM651 does not utilize a VVT system. With this being introduced in 2008 I believe the first diesel to have it was from Mitsubishi around 2010.
I appreciate you looking out and couldn't agree more. The traffic here is terrible! I do not plan on having it as a daily driver. More so as a vehicle to enjoy long trips in. I am a fan and I think I would prefer it to a 213 for the "somewhat simpler DIY maint experience"
With that, I did do a long test drive from DC to NY in a 213 All road and found myself feeling mixed with it. Might need more seat time. Of course its a bigger discussion better served on another thread
Now a 2014-16 E400 wagon from Canada as a daily? That would be a sweet package for the money.
For what it's worth you're dealing with similar issues of artificially kept low oil pressure on your OM651 diesel.
You've confirmed the oil pump normal pressure can be enabled by disconnecting solenoid.
You'll need to confirm how to deal with your piston squirters solenoid. Specifically make sure that unplugging squirters solenoid does enable squirting ?
As far as squirting goes dry pistons with rings stuck by carbonized oil solids... cause drafty unbalanced cylinders with stock setup!
The best way to cool pistons is at normal driving Rpm so oil is never exposed to vaporizing temperatures.
You may need to switch viscosity to spray at needed 1600Rpm... not starting above 2k for ineffective spray cooling.
Not having hydraulic VVT prevent corruption of ECU timings with jerky camshaft positions as in MOD-1.
LET'S GET ONE THING STRAIGHT.... Low viscosity thin-film oils are not best at preventing engine frictions. Where torque's involved you want an effective film cushion.
Last edited by CaliBenzDriver; Feb 13, 2025 at 01:39 AM.
I didn't pay much attention to the selling point of their upgraded pumps... more along the lines of proof that the design philosophy is flawed, and that any steps that can be taken to reverse this philosophy, say, by unplugging the worthless solenoid that surely has a hand in the causing issues in these engines.
Unplug, step up to a better (higher viscosity) engine oil, and let the engine work in a manner that doesn't destroy itself in the process.
I subscribe to that!
It's amazing how common sense can still get lost in 21st century.
Last edited by CaliBenzDriver; Feb 13, 2025 at 04:24 AM.
A 2012 study on the effects of cooling jets being switch on or off for Diesel. Study mentioned Gas model studies being similar. Scroll down to see the study without signing up
Right around the time when the W212 was well in production. Its interesting seeing all the temperature changes
The study examines the impact of piston cooling jets (PCJs) on engine performance, emissions, and fuel consumption in a Ford 2.4L diesel engine. A solenoid-controlled system was used to switch the jets on and off, allowing analysis of their effects under different conditions.
Key Findings
Piston Temperature Impact
Switching off the jets increased piston temperatures by 23–88°C, with the combustion bowl bottom experiencing the largest rise.
Cooling jets significantly influenced temperature distribution, with the fastest response occurring when switching them on.
Effect on Engine Thermal State
With jets off, engine oil temperature dropped, while liner temperatures increased.
The jets redirected heat to the bulk oil, which then transferred it to the coolant system.
Impact on Emissions
NOx increased by ~3% with jets off.
CO emissions decreased by 5-10%.
HC emissions showed minor reductions.
Fuel Consumption
At high speed, low load, fuel consumption decreased when jets were off.
At low speed, high load, fuel consumption increased when jets were off.
Across the NEDC cycle, the overall fuel consumption difference was negligible.
Oil System & Pump Load
Turning jets on caused a drop in oil pressure (~0.4–1 bar).
Oil pump frictional losses increased slightly when jets were off.
Effectiveness of Active Jet Control
Selective switching strategies showed small reductions in CO (2.3-5.7%) and slight increases in NOx (0.2-1.2%).
Fuel economy improvements from switching were negligible.
Conclusion
The study found no significant benefit in actively controlling PCJs for emissions or fuel economy improvements. While PCJs effectively reduced piston temperature and had minor effects on emissions, the trade-offs in NOx increase and oil system complexity make an on/off strategy unjustifiable in practical applications.
Last edited by KristiyanPetrov; Feb 13, 2025 at 04:37 PM.
Thank you Sargy & Kristiyan for doc + summary. It's an interesting read because it deals with a practical study.
This research study deals with 4Cyl Ford turbo diesel.
Numbers are slightly different but work in the same way so the findings presented are clearly meaningful for our gasoline NA/TT engines.
research conclusions oil pressure vs. sprayers
Oil pressure drops when squirters open up... duh!
piston heat
Piston passes 240°C after 1mn without active spray cooling how heat gets stored
When oil stops removing piston heat, the oil gets cooler: duh!
So this confirms:
Hot oil = cool pistons
cool oil = hot pistons
With MOD-4 you're going to see faster warming oil at normal driving Rpm.
(At idle Rpm oil/coolant are hardly circulated... don't idle to warmup!)
> DUAL-SOLENOID OIL CONTROL:
The important thing I understood for diesel engines setup is to not enable sprayers unless you also have enabled normal pump pressure else you'll get oil starvation failure.
> POWERED VS. UNPOWERED:
Again these solenoid valves have the potential to jam when you least expect it: RIP!
Double check what activate the status you want : is it powered or unpowered/unplugged?
We can assume unplugged is a safe-mode but you don't want to risk an engine to find out.
>SILENT MISSINGS: The study keeps dry pistons out of the context of engine applications.
There's no correlation made between dry piston temperature and :
oil vaporize flash-point,
rings getting carbon jammed.
drafty crankcase pressure
unbalanced cylinders contribution
extreme stored heat
jerky VVT positioning
I am going to agree that dry pistons does save engine energy, at the expense of basic functions.
When considering Pro & Cons there's no good reason standing to make up for disrupting the ECU/TCU controls.
Last edited by CaliBenzDriver; Feb 14, 2025 at 04:27 AM.
Update: Going past 3,500km with the oil pump always in "full" pressure mode
Have to say I doubted CaliBenzDriver when he said the ECU will take time to adapt (I've always been running Amsoil 5w40)
But the M276 definitely feels "tighter" and very responsive, if that makes sense. Start-ups are immediate, almost no crank-time at all. She has 118k miles and runs smooth and strong, zero oil consumption.
We've had a lot of snow here in Toronto recently, I was flying up some country roads yesterday, 100kph full-throttle with a rooster tail of snow behind me. Engine smooth as butter.
Update: Going past 3,500km with the oil pump always in "full" pressure mode
Have to say I doubted CaliBenzDriver when he said the ECU will take time to adapt (I've always been running Amsoil 5w40)
But the M276 definitely feels "tighter" and very responsive, if that makes sense. Start-ups are immediate, almost no crank-time at all. She has 118k miles and runs smooth and strong, zero oil consumption.
We've had a lot of snow here in Toronto recently, I was flying up some country roads yesterday, 100kph full-throttle with a rooster tail of snow behind me. Engine smooth as butter.
Update: Going past 3,500km with the oil pump always in "full" pressure mode
Have to say I doubted CaliBenzDriver when he said the ECU will take time to adapt (I've always been running Amsoil 5w40)
But the M276 definitely feels "tighter" and very responsive, if that makes sense. Start-ups are immediate, almost no crank-time at all. She has 118k miles and runs smooth and strong, zero oil consumption.
We've had a lot of snow here in Toronto recently, I was flying up some country roads yesterday, 100kph full-throttle with a rooster tail of snow behind me. Engine smooth as butter.
@Bertie_
With only 3500kMeters, this is just the beginning, a small preview of what you may get!
Your ECU is now responding to your engine setup improvements with more precise controls. It's rebuilding appropriate fuel maps.
Your throttle is going to keep improving, this is directly going to help your tranny be the best you ever had.... seemless shifts.
Around 10kMiles gradually upgrade your Amsoil signature to 5w50 for effective spraying. This wil further refine VVT timings (that get corrupted by sprayers pressure drop).
How long have you used Amsoil 5w40 in your 118kMi engine??
Does Amsoil turn into black sludge when replacing it 5 or 10kMi?
Amsoil for the last 28k miles, oil changes every 3k miles on average. It's dark but not "black sludge" at 3k miles
Before that it was dealer-serviced at the Benz dealer since new, ~8-10k mile oil changes (annual). There was varnish you could see through the oil fill cap.
Amsoil for the last 28k miles, oil changes every 3k miles on average. It's dark but not "black sludge" at 3k miles
Before that it was dealer-serviced at the Benz dealer since new, ~8-10k mile oil changes (annual). There was varnish you could see through the oil fill cap.
That varnish is all gone today.
28kMi, every 3kMi that's great!
You've been using superior Amsoil signature to keep engine delosit free and cool with premium PAO.
Your engine may very well be ready to experiment upgrading to effective spraying at driving Rpm.
This is the real deal!
It will provide your ECU stable pressure to control VVT position (changing viscosity will also confuse ECU/TCU for 500 to 1kMi juste like you experienced when switching to Amsoil sig. )
I am not familiar with available Amsoil PAO product line.
You'd want to do an intermediate step like a 10/15W40 then onto 0/5w50.
Last edited by CaliBenzDriver; Feb 17, 2025 at 06:15 AM.
after a few hundred miles since the last post, I have also noticed the no-crank start. shifts have remained smooth, and with the acceleration in 4th gear while in E merging onto the freeway has been exceptionally strong.
after a few hundred miles since the last post, I have also noticed the no-crank start. shifts have remained smooth, and with the acceleration in 4th gear while in E merging onto the freeway has been exceptionally strong.
You deserve all of this...
Paying attention to engine needs allows the ECU to run efficient timings and TCU to adapt shifts.
The cherry on the cake is normal heat mgt to prevent oil-in-harness - Performance without drama is just gonna be a great Mercedes.
Last edited by CaliBenzDriver; Feb 19, 2025 at 06:33 PM.
this may NOT be the "pump solenoid" but a misc filter assembly solenoid... the pump control solenoid is built INSIDE THE ENG OIL PUMP itself. Find your engine pump diagram
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
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